[Xen-devel] [PATCH v4 20/32] libxl_qmp: Handle write to QMP socket

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

The libxl__ev_qmp_* will now send the command to QEMU when the socket is
ready for writes.

Signed-off-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
---
 tools/libxl/libxl_qmp.c | 44 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/tools/libxl/libxl_qmp.c b/tools/libxl/libxl_qmp.c
index 2792f35912..75f953d521 100644
--- a/tools/libxl/libxl_qmp.c
+++ b/tools/libxl/libxl_qmp.c
@@ -1326,6 +1326,8 @@ static int qmp_ev_prepare_cmd(libxl__gc *gc,
     ev->tx_buf = buf;
     ev->tx_buf_len = len;
 
+    libxl__ev_fd_modify(gc, &ev->qmp_efd, ev->qmp_efd.events | POLLOUT);
+
     return 0;
 }
 
@@ -1435,6 +1437,43 @@ static int qmp_ev_callback_readable(libxl__egc *egc, 
libxl__ev_qmp *ev, int fd)
     return 0;
 }
 
+static int qmp_ev_callback_writable(libxl__gc *gc, libxl__ev_qmp *ev, int fd)
+{
+    int rc;
+    char *buf;
+    size_t len;
+    int buf_fd = -1;
+
+    /* No need to call qmp_ev_callback_writable again, everything that needs to
+     * be send for now will be in this call. */
+    libxl__ev_fd_modify(gc, &ev->qmp_efd, ev->qmp_efd.events & ~POLLOUT);
+
+    if (ev->qmp_state == qmp_state_connected) {
+        if (!ev->tx_buf)
+            return 0;
+
+        buf = ev->tx_buf;
+        len = ev->tx_buf_len;
+        buf_fd = libxl__carefd_fd(ev->cfd);
+
+        ev->tx_buf = NULL;
+    } else {
+        return 0;
+    }
+
+    LOG_QMP("sending: '%.*s'", (int)len, buf);
+
+    if (buf_fd >= 0) {
+        rc = libxl__sendmsg_fds(gc, fd, buf, len, 1, &buf_fd, "QMP socket");
+    } else {
+        rc = libxl_write_exactly(CTX, fd, buf, len,
+                                 "QMP command", "QMP socket");
+    }
+
+    free(buf);
+    return rc;
+}
+
 static void qmp_ev_callback_error(libxl__egc *egc, libxl__ev_qmp *ev)
 {
     EGC_GC;
@@ -1470,6 +1509,11 @@ static void qmp_ev_fd_callback(libxl__egc *egc, 
libxl__ev_fd *ev_fd,
         return;
     }
 
+    if (revents & POLLOUT) {
+        rc = qmp_ev_callback_writable(gc, ev, fd);
+        if (rc)
+            goto out;
+    }
     if (revents & POLLIN) {
         rc = qmp_ev_callback_readable(egc, ev, fd);
         if (rc)
-- 
Anthony PERARD


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